Apple has announced Jeff Williams as its new chief operating officer and Johny Srouji is joining Apple’s executive team as senior vice president for Hardware Technologies.Apple announced a series of changes to its leadership team this morning, including, most notably, the promotion of Jeff Williams to COO, a role that had not been filled since Tim Cook became Apple CEO in 2011.On Thursday, Cook announced that Jeff Williams will be promoted to chief operations officer, a job that has been vacant since Cook became chief executive in 2011.

The appointment was part of several management changes at the world’s most valuable company, including the elevation of a top engineer who has been in charge of designing chips that are at the heart of the iPhone and iPad. Williams has effectively been Apple’s COO for some time, but CEO Tim Cook has left the title unclaimed since he vacated it to take the reins from an ailing Steve Jobs in 2011. It has also appointed former US marketing agency executive Tor Myhren as vice president of marketing communications, reporting directly to chief executive Tim Cook. In addition, Apple says it’s expanding VP of Worldwide Marketing Phil Schiller’s duties to now include running the App Store across all Apple platforms. Williams, who joined Apple in 1998, has been one of Cook’s most trusted deputies and has seen his role expand over the past five years; it includes managing Apple’s vast supply chain.

According to a report from The WSJ citing an unnamed senior exec, the move to appoint Williams to the COO position was more about formalizing a role he was already playing inside the company, rather than an indication that he could become Apple’s next CEO when Cook departs. Williams also vets potential acquisitions, coordinates with Foxconn Technology Group and other manufacturers, and oversees the logistics needed to get millions of devices from Asian factories to stores around the world. Myhren joins from Grey Group, where he has served as chief creative officer and president of Grey New York, and succeeds Hiroki Asai, who earlier announced plans to retire after 18 years at Apple. Since 2010, he has overseen Apple’s supply chain, service and support, and social responsibility initiatives. “Jeff played a key role in Apple’s entry into the mobile phone market with the launch of iPhone and he continues to supervise development of Apple’s first wearable product, Apple Watch,” said a statement from Apple.

According to the Apple, he will be responsible for Apple’s advertising efforts and also its interactive web design, packaging and retail store displays. Apple says that, in his new position, Schiller will focus on expanding Apple’s ecosystem across devices, including iPhone, iPad, Mac, Apple Watch and Apple TV. Both, however, have not yet seen the same impact in terms of breakout hits or developer traction as the original App Store did, though it’s still early days. Heralded by the Haaretz newspaper as the highest-ranking Israeli in Silicon Valley, Srouji previously held senior positions at Intel Corp. and International Business Machines Corp.

Apple has been investing heavily in semiconductors, and unlike many other handset makers, it designs its own chips instead of buying whatever the latest product is from outside suppliers. Apple declined to comment on succession, but has said in the past that it has a plan in place and that different members of its executive team could step in. “These strategic moves fit like a glove, as Apple needed to fill the COO vacancy heading into a pivotal 2016,” said Daniel Ives, managing director at FBR Capital Markets. “They really need to boost that bench behind Cook.” The appointments come at a critical time.